Document the BUILD_WORKSPACE_DIRECTORY and BUILD_WORKING_DIRECTORY environment variables.
Document the BUILD_WORKSPACE_DIRECTORY and BUILD_WORKING_DIRECTORY environment variables.

Fixes #6612.

RELNOTES: None.
PiperOrigin-RevId: 233582818

davidzchen/bazel,aehlig/bazel,aehlig/bazel,meteorcloudy/bazel,aehlig/bazel,twitter-forks/bazel,perezd/bazel,ulfjack/bazel,katre/bazel,twitter-forks/bazel,bazelbuild/bazel,dslomov/bazel-windows,ulfjack/bazel,ButterflyNetwork/bazel,aehlig/bazel,davidzchen/bazel,cushon/bazel,twitter-forks/bazel,akira-baruah/bazel,ulfjack/bazel,dslomov/bazel,katre/bazel,perezd/bazel,ulfjack/bazel,safarmer/bazel,bazelbuild/bazel,twitter-forks/bazel,ButterflyNetwork/bazel,meteorcloudy/bazel,perezd/bazel,dslomov/bazel,dslomov/bazel-windows,werkt/bazel,twitter-forks/bazel,safarmer/bazel,ButterflyNetwork/bazel,dslomov/bazel,ulfjack/bazel,safarmer/bazel,cushon/bazel,dslomov/bazel,twitter-forks/bazel,cushon/bazel,aehlig/bazel,ulfjack/bazel,dslomov/bazel-windows,perezd/bazel,meteorcloudy/bazel,dslomov/bazel-windows,cushon/bazel,dslomov/bazel-windows,akira-baruah/bazel,safarmer/bazel,dslomov/bazel,ButterflyNetwork/bazel,katre/bazel,bazelbuild/bazel,dslomov/bazel,akira-baruah/bazel,davidzchen/bazel,aehlig/bazel,safarmer/bazel,akira-baruah/bazel,ButterflyNetwork/bazel,aehlig/bazel,katre/bazel,akira-baruah/bazel,werkt/bazel,davidzchen/bazel,perezd/bazel,bazelbuild/bazel,katre/bazel,bazelbuild/bazel,meteorcloudy/bazel,davidzchen/bazel,cushon/bazel,katre/bazel,werkt/bazel,werkt/bazel,davidzchen/bazel,twitter-forks/bazel,werkt/bazel,ButterflyNetwork/bazel,bazelbuild/bazel,davidzchen/bazel,dslomov/bazel,werkt/bazel,meteorcloudy/bazel,meteorcloudy/bazel,meteorcloudy/bazel,ulfjack/bazel,dslomov/bazel-windows,cushon/bazel,perezd/bazel,perezd/bazel,akira-baruah/bazel,safarmer/bazel